How to preserve font color when converting PDF to image in PHP

In recent years, with the widespread use of PDF files, there is an increasing need to convert PDF files into images for easy display and sharing. For developers, how to implement this process has become a hot topic. In the process of converting PDF to images, not only the quality of the images must be considered, but also the color of the fonts. This article will introduce how to use PHP language to preserve the font color when converting PDF to images.

1. Why does the font color change when converting PDF to an image?

In PDF files, all processes are vector operations and there is no actual color value. Instead, each element in a PDF file is a set of instructions that describe how to draw shapes and fill colors on the page, among other things. These instructions include the colors to use and how to fill or stroke the shape. When printing or generating PDF files, these instructions are converted into color-specific vector graphics and displayed to the user.

In the process of converting a PDF file into an image, these instructions in the PDF file need to be converted into actual color values. This is why the font color is changed when the PDF is converted into an image.

2. How to use PHP to retain font color

There are many commonly used PHP libraries for converting PDF into images, such as imagick, Ghostscript, etc. This article mainly introduces how to use the pdf2image library to preserve font colors when converting PDF to images.

1. Install the pdf2image library

When using the pdf2image library in PHP, you need to install the library first. You can install it in the command line through the following command:

composer require spatie/pdf-to-image

2. Implementation code

The following is how to use the pdf2image library in PHP to convert PDF into pictures and retain font colors. Sample code:

use Spatie\PdfToImage\Pdf;

$pdf = new Spatie\PdfToImage\Pdf('example.pdf');
$pdf->setCompressionQuality(100);
$pdf->setPage(1);
$pdf->setImageFormat('png');
$pdf->saveImage('/path/to/save/image.png');

Among them, $pdf->setCompressionQuality(100) means setting the image compression quality to 100%, $pdf->setPage(1) means selecting the first page of the PDF file as the converted The page of the image, $pdf->setImageFormat('png') means converting PDF to a picture in PNG format, $pdf->saveImage('/path/to/save/image.png') means converting the converted Save the image to the specified path.

Converting PDF to images and retaining font colors through this code is implemented through the pdf2image library.

3. Conclusion

In this article, we introduced why the font color changes when PDF is converted to an image, and how to apply PHP's pdf2image library to achieve font color preservation during the conversion process. . Converting PDF to images is a common and important function. When you encounter corresponding needs during development, you can quickly implement it through the methods mentioned in this article.

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